package Queue;

public class LoopQueue<E> implements Queue<E> {

    private E[] data;

    private int front,tail;
    private int size;

    public LoopQueue(){
        this(5);
    }

    public LoopQueue(int capacity){
        data = (E[])new Object[capacity + 1];
        front = 0;
        tail = 0;
        size = 0;
    }

    @Override
    public void enqueue(E e) {
        if ((tail + 1) % data.length == front) {
            resize(getCapacity() << 1);
        }

        data[tail] = e;
        tail = (tail+1)%data.length;
        size++;
    }

    public void resize(int newCapacity){
        E[] newData = (E[])new Object[newCapacity+1];
        for (int i = 0; i < size; i++) {
            newData[i] = data[(i+front)%data.length];
        }
        data = newData;
        front = 0;
        tail = size;
        newData = null;
    }

    @Override
    public E dequeue() {
        if (isEmpty()) {
            throw new RuntimeException("队列为空");
        }
        E result = data[front];
        data[front] = null;
        front = (front + 1) % data.length;
        size --;
        if (size == getCapacity()/4 &&getCapacity()/2 !=0) {
            resize(getCapacity() >> 1);
        }
        return result;
    }

    @Override
    public E getFront() {
        return null;
    }

    @Override
    public int getSize() {
        return size;
    }

    @Override
    public boolean isEmpty() {
        return front == tail;
    }

    @Override
    public int getCapacity() {
        return data.length - 1;
    }

    //    private static class Node<E>{
//        Node preNode;
//        Node nextNode;
//        private E e;
//        public Node(E e){
//           this.e = e;
//        }
//    }
//
//    private Node<E> startNode;

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append("ArrayStack capacity:"+data.length+"size:"+size+",front:[");
        for (int i = front; i !=tail; i = (i+1) %data.length) {
            sb.append(data[i]);
            if ((i+1)%data.length != tail) {
                sb.append(",");
            }
        }
        return sb.append("] tail").toString();
    }

    public static void main(String[] args) {
        Queue<Integer> queue = new LoopQueue<Integer>(10);
        for (int i = 0; i < 10; i++) {
            queue.enqueue(i);
            System.out.println(queue);

            if (i%3==2) {
                queue.dequeue();
                System.out.println(queue);
            }
        }
    }
}
